In recent years, an automatic identification technology using wireless communication has been actively developed and has been introduced into some fields. The automatic identification technology includes a wireless communication device which stores information in an electronic circuit, a reader/writer which reads and writes information stored in the wireless communication device, and a higher-order system which performs processing of read information, control of the reader/writer, and the like. The wireless communication device is referred to as various names such as an RFID tag, an IC tag, and a wireless tag. Further, the wireless communication device often has no battery. In such a case, the wireless communication device is operated by an electromagnetic wave emitted from the reader/writer and wirelessly communicates with the reader/writer. As the higher-order device for controlling the wireless communication device and the reader/writer, a computer is typically used and communicates with the reader/writer through a parallel port, a serial port (typically, a universal serial bus (USB) port), or the like. The automatic identification technology has been expected as a technology for comprehensively managing production, distribution, and retail of products. Therefore, a wireless communication device which is inexpensive, small, and highly convenient has been developed.
Along with the development of the automatic identification technology, the automatic identification technology is applied not only to manage distribution but also to a system for managing personal belongings and searching a lost article (e.g., Patent Document 1: Japanese Published Patent Application No 2005-003627). A lost article searching system in Patent Document 1 is a system that can detect a position of an object to be searched by attaching a wireless communication device to the object to be searched and specifying a position of the wireless communication device.